What you can expect

To start, your doctor will want to get an idea of your peak flow measurements when you feel good and have no asthma symptoms.

Measurements from a peak flow meter are called your peak flow rate. You'll record your daily peak flow rate over a two- to three-week period. Your highest peak flow rate over this period is known as your "personal best." Your personal best serves as a benchmark in your daily asthma management plan.

When to check your peak flow

Your doctor will probably recommend using your peak flow meter once a day — typically before you take your regular asthma medication in the morning.

If your asthma is under control most of the time, your doctor may say it's OK to check your peak flow every few days instead of every day. If your asthma isn't very well controlled, you may need to take peak flow readings more than once a day.

In addition to regular peak flow monitoring, you may need to check your peak flow in these situations:

You have asthma symptoms that wake you up at night.

You have increased symptoms during the day.

You have a cold, flu or other illness that affects your breathing.

You need to use quick-relief (rescue) medication, such as inhaled albuterol. (Check your peak flow before you take rescue medication. Then check it again after 20 or 30 minutes.)

Tracking your readings

Record your peak flow rate in an asthma diary. Some people record their peak flow meter readings by hand. But if you have an electronic personal health record, you may choose to enter your information into the record using a computer or mobile device. This gives you the option of sharing your data with your health care providers and family members. Some peak flow meters upload this data automatically.

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